Multi mode mobile computing devices have been proposed which have multiple capabilities. For example, mobile telephones might be expected to undertake personal computing tasks now undertaken by notebook computers, in addition to their communication functions.
As recognized herein, multiple processors might be required to support multiple modes of operation. As also recognized herein, using the same internal operation independent of the operational mode means that a main processor typically functions as a master device that controls peripheral devices and that treats the other device processors (e.g., a telephone modem processor) as peripherals. Such a design requires that the main processor be active in all modes, including, e.g., the main processor needs to be active in the telephone mode, in which the modem processor is active, simply to provide the modem processor access to device hardware (e.g., a data display, non volatile storage, audio input/output) that is controlled by the main processor. In other words the main processor is here simply mediating on behalf of the modem processor, because the hardware architecture does not allow the modem processor direct access to some of the hardware resources in the device.
As understood herein, it would be advantageous to minimize when possible, the use of hardware intermediaries (such as the main processor in the example above) to allow power efficient execution of tasks, to conserve the battery. Moreover by use of methods described in this invention it may be possible to power off processors that don't need to serve such intermediary role further extending device battery life. Furthermore, requiring a single main processor to always function as a device master means that software and software changes that might apply only to a modem processor must be coordinated or otherwise integrated with the main processor as well, complicating software management. In particular the large base of software presently available for cellular phone type devices, which functions on the modem processor cannot be used unchanged in a device in which the modem processor is a peripheral to a main application processor. The present invention can allow the reuse of this large base legacy of application software by architecting the hardware so that it appears to the legacy software as it would in current single processor devices.